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Flashcards in Third Week of Development Deck (12):
1

Gastrulation

process of establishing 3 germ layers and begins with the formation of the primitive streak

2

Cells of the epiblast migrate towards to the primitive streak, detach, and slip underneath the epiblast in a process called what?

invagination

3

Mesenchymal cells migrate cranially from the primitive node and pit forming a median celluar cord called what?

the notochordal process, this process aquires a lumen known as the notochordal canal

4

The prechordal plate will be important in the develpment of the _____ while the notochord will be the basis for the formation of the parts of the ____________________.

forebrain, axial skeleton and spinal cord

5

What does the cloacal membrane form?

the anus

6

When are body axes formed?

before and during the time of gastrulation

7

When does the primitive streak regress?

the end of the fourth week

8

The beginning of the 3rd week of development (gastrulation) is a highly sensitive period for what?

teratogenesis and malformations

9

Holoprosencephaly

high doses of alcohol at the gastrulation stage kills cells in the anterior midline of the germ disc producing a deficiency of the midline in craniofacial structures, fore brain is small

10

Sirenomelia

insufficient mesoderm formed in the caudal most region of the embryo , abnormalities in the lower half of body, absent of fused lower limbs (sometimes associated with maternal diabetes)

11

Situs inversus

left and right organ positions are reversed

12

Sacrococcygeal teratoma TEST QUESTION

proliferation of remnants of the primitive streak, forms tumors in all 3 germ layers, most common tumor in newborns